Comedians can be as offensive as they want, because they're comedians. Unlike news organizations or politicians, comedians don't have an obligation to serve a public or a citizenry. Their primary function is to entertain -- and sometimes that means turning a few people off.
Still, that doesn't mean that their words don't shape the way we think. That's why I want to take a moment to talk about how often the phrase "illegal immigrant" has been used in recent comedic bits, despite the fact that about half of American Latinos find the term offensive.